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Gao Y, Shen Y, Fan J, Ding H, Zheng B, Yu H, Huang S, Kong Q, Lv H, Zhuo X, Lu S. Establishment and application of an iELISA detection method for measuring apical membrane antigen 1 (AMA1) antibodies of Toxoplasma gondii in cats. BMC Vet Res 2023; 19:229. [PMID: 37924072 PMCID: PMC10623812 DOI: 10.1186/s12917-023-03775-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 10/05/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND Diseases caused by Toxoplasma gondii (T. gondii) have introduced serious threats to public health. There is an urgent need to develop a rapid detection method for T. gondii infection in cats, which are definitive hosts. Recombinant apical membrane antigen 1 (rAMA1) was produced in a prokaryotic expression system and used as the detection antigen. The aim of this study was to evaluate and optimize a reliable indirect enzyme-linked immunosorbent assay (iELISA) method based on rAMA1 for the detection of antibodies against T. gondii in cats. RESULTS The rAMA1-iELISA method was developed and optimized by the chessboard titration method. There were no cross-reactions between T. gondii-positive cat serum and positive serum for other pathogens, indicating that rAMA1-iELISA could only detect T. gondii in most cases. The lowest detection limit of rAMA1-iELISA was 1:3200 (dilution of positive serum), and the CV of repeated tests within batches and between batches were confirmed to be less than 10%. The results of 247 cat serum samples detected by rAMA1-iELISA (kappa value = 0.622, p < 0.001) were in substantial agreement with commercial ELISA. The ROC curve analysis revealed the higher overall check accuracy of rAMA1-iELISA (sensitivity = 91.7%, specificity = 93.6%, AUC = 0.956, 95% CI 0.905 to 1.000) than GRA7-based iELISA (sensitivity = 91.7%, specificity = 85.5%, AUC = 0.936, 95% CI 0.892 to 0.980). Moreover, the positive rate of rAMA1-iELISA (6.5%, 16/247) was higher than that of GRA7-based iELISA (3.6%, 9/247) and that of commercial ELISA kit (4.9%, 12/247). CONCLUSION The iELISA method with good specificity, sensitivity, and reproducibility was established and can be used for large-scale detection of T. gondii infection in clinical cat samples.
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Affiliation(s)
- Yafan Gao
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Yu Shen
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Jiyuan Fan
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Haojie Ding
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Bin Zheng
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Haijie Yu
- Jiaxing Vocational & Technical College, Jiaxing, 314036, China
| | - Siyang Huang
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China
| | - Qingming Kong
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Hangjun Lv
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China
| | - Xunhui Zhuo
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China.
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China.
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China.
| | - Shaohong Lu
- School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, 310013, China.
- Engineering Research Center of Novel Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China.
- Key Laboratory of Bio-Tech Vaccine of Zhejiang Province, Hangzhou Medical College, Hangzhou, China.
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Najm R, Ruivo MTG, Penarete-Vargas DM, Hamie M, Mouveaux T, Gissot M, Boulanger MJ, El Hajj H, Lebrun M. Invasion of Toxoplasma gondii bradyzoites: Molecular dissection of the moving junction proteins and effective vaccination targets. Proc Natl Acad Sci U S A 2023; 120:e2219533120. [PMID: 36693095 DOI: 10.1073/pnas.2219533120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Toxoplasmosis is a neglected parasitic disease necessitating public health control. Host cell invasion by Toxoplasma occurs at different stages of the parasite's life cycle and is crucial for survival and establishment of infection. In tachyzoites, which are responsible for acute toxoplasmosis, invasion involves the formation of a molecular bridge between the parasite and host cell membranes, referred to as the moving junction (MJ). The MJ is shaped by the assembly of AMA1 and RON2, as part of a complex involving additional RONs. While this essential process is well characterized in tachyzoites, the invasion process remains unexplored in bradyzoites, which form cysts and are responsible for chronic toxoplasmosis and contribute to the dissemination of the parasite between hosts. Here, we show that bradyzoites invade host cells in an MJ-dependent fashion but differ in protein composition from the tachyzoite MJ, relying instead on the paralogs AMA2 and AMA4. Functional characterization of AMA4 reveals its key role for cysts burden during the onset of chronic infection, while being dispensable for the acute phase. Immunizations with AMA1 and AMA4, alone or in complex with their rhoptry neck respective partners RON2 and RON2L1, showed that the AMA1-RON2 pair induces strong protection against acute and chronic infection, while the AMA4-RON2L1 complex targets more selectively the chronic form. Our study provides important insights into the molecular players of bradyzoite invasion and indicates that invasion of cyst-forming bradyzoites contributes to cyst burden. Furthermore, we validate AMA-RON complexes as potential vaccine candidates to protect against toxoplasmosis.
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Abstract
Apicomplexa are obligatory intracellular parasites that sense and actively invade host cells. Invasion is a conserved process that relies on the timely and spatially controlled exocytosis of unique specialized secretory organelles termed micronemes and rhoptries. Microneme exocytosis starts first and likely controls the intricate mechanism of rhoptry secretion. To assemble the invasion machinery, micronemal proteins-associated with the surface of the parasite-interact and form complexes with rhoptry proteins, which in turn are targeted into the host cell. This review covers the molecular advances regarding microneme and rhoptry exocytosis and focuses on how the proteins discharged from these two compartments work in synergy to drive a successful invasion event. Particular emphasis is given to the structure and molecular components of the rhoptry secretion apparatus, and to the current conceptual framework of rhoptry exocytosis that may constitute an unconventional eukaryotic secretory machinery closely related to the one described in ciliates. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Marta Mendonça Cova
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
| | - Mauld H Lamarque
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
| | - Maryse Lebrun
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
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Jiang L, Liu B, Hou S, Su T, Fan Q, Alyafeai E, Tang Y, Wu M, Liu X, Li J, Hu Y, Li W, Zheng Z, Liu Y, Wu J. Discovery and evaluation of chalcone derivatives as novel potential anti-Toxoplasma gondii agents. Eur J Med Chem 2022; 234:114244. [DOI: 10.1016/j.ejmech.2022.114244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/20/2022] [Accepted: 02/26/2022] [Indexed: 01/08/2023]
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Ben Chaabene R, Lentini G, Soldati-Favre D. Biogenesis and discharge of the rhoptries: Key organelles for entry and hijack of host cells by the Apicomplexa. Mol Microbiol 2021; 115:453-465. [PMID: 33368727 DOI: 10.1111/mmi.14674] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 12/14/2022]
Abstract
Rhoptries are specialized secretory organelles found in the Apicomplexa phylum, playing a central role in the establishment of parasitism. The rhoptry content includes membranous as well as proteinaceous materials that are discharged into the host cell in a regulated fashion during parasite entry. A set of rhoptry neck proteins form a RON complex that critically participates in the moving junction formation during invasion. Some of the rhoptry bulb proteins are associated with the membranous materials and contribute to the formation of the parasitophorous vacuole membrane while others are targeted into the host cell including the nucleus to subvert cellular functions. Here, we review the recent studies on Toxoplasma and Plasmodium parasites that shed light on the key steps leading to rhoptry biogenesis, trafficking, and discharge.
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Affiliation(s)
- Rouaa Ben Chaabene
- Department of Microbiology and Molecular Medicine, CMU, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Gaëlle Lentini
- Department of Microbiology and Molecular Medicine, CMU, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, CMU, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Muñiz-Hernández S, Luna-Nophal A, León CTG, Domínguez-Ramírez L, Patrón-Soberano OA, Nava-Castro KE, Ostoa-Saloma P, Morales-Montor J. Dehydroepiandrosterone Effect on Toxoplasma gondii: Molecular Mechanisms Associated to Parasite Death. Microorganisms 2021; 9:513. [PMID: 33801356 DOI: 10.3390/microorganisms9030513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 11/21/2022] Open
Abstract
Toxoplasmosis is a zoonotic disease caused by the apicomplexa protozoan parasite Toxoplasma gondii. This disease is a health burden, mainly in pregnant women and immunocompromised individuals. Dehydroepiandrosterone (DHEA) has proved to be an important molecule that could drive resistance against a variety of infections, including intracellular parasites such as Plasmodium falciparum and Trypanozoma cruzi, among others. However, to date, the role of DHEA on T. gondii has not been explored. Here, we demonstrated for the first time the toxoplasmicidal effect of DHEA on extracellular tachyzoites. Ultrastructural analysis of treated parasites showed that DHEA alters the cytoskeleton structures, leading to the loss of the organelle structure and organization as well as the loss of the cellular shape. In vitro treatment with DHEA reduces the viability of extracellular tachyzoites and the passive invasion process. Two-dimensional (2D) SDS-PAGE analysis revealed that in the presence of the hormone, a progesterone receptor membrane component (PGRMC) with a cytochrome b5 family heme/steroid binding domain-containing protein was expressed, while the expression of proteins that are essential for motility and virulence was highly reduced. Finally, in vivo DHEA treatment induced a reduction of parasitic load in male, but not in female mice.
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Wong ZS, Borrelli SLS, Coyne CC, Boyle JP. Cell type- and species-specific host responses to Toxoplasma gondii and its near relatives. Int J Parasitol 2020; 50:423-431. [PMID: 32407716 PMCID: PMC8281328 DOI: 10.1016/j.ijpara.2020.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 10/24/2022]
Abstract
Toxoplasma gondii is remarkably unique in its ability to successfully infect vertebrate hosts from multiple phyla and can successfully infect most cells within these organisms. The infection outcome in each of these species is determined by the complex interaction between parasite and host genotype. As techniques to quantify global changes in cell function become more readily available and precise, new data are coming to light about how (i) different host cell types respond to parasitic infection and (ii) different parasite species impact the host. Here we focus on recent studies comparing the response to intracellular parasitism by different cell types and insights into understanding host-parasite interactions from comparative studies on T. gondii and its close extant relatives.
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Affiliation(s)
- Zhee S Wong
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Sarah L Sokol Borrelli
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Carolyn C Coyne
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Jon P Boyle
- Department of Biological Sciences, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, United States.
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8
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Horta MF, Andrade LO, Martins-Duarte ÉS, Castro-Gomes T. Cell invasion by intracellular parasites - the many roads to infection. J Cell Sci 2020; 133:133/4/jcs232488. [PMID: 32079731 DOI: 10.1242/jcs.232488] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Intracellular parasites from the genera Toxoplasma, Plasmodium, Trypanosoma, Leishmania and from the phylum Microsporidia are, respectively, the causative agents of toxoplasmosis, malaria, Chagas disease, leishmaniasis and microsporidiosis, illnesses that kill millions of people around the globe. Crossing the host cell plasma membrane (PM) is an obstacle these parasites must overcome to establish themselves intracellularly and so cause diseases. The mechanisms of cell invasion are quite diverse and include (1) formation of moving junctions that drive parasites into host cells, as for the protozoans Toxoplasma gondii and Plasmodium spp., (2) subversion of endocytic pathways used by the host cell to repair PM, as for Trypanosoma cruzi and Leishmania, (3) induction of phagocytosis as for Leishmania or (4) endocytosis of parasites induced by specialized structures, such as the polar tubes present in microsporidian species. Understanding the early steps of cell entry is essential for the development of vaccines and drugs for the prevention or treatment of these diseases, and thus enormous research efforts have been made to unveil their underlying biological mechanisms. This Review will focus on these mechanisms and the factors involved, with an emphasis on the recent insights into the cell biology of invasion by these pathogens.
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Affiliation(s)
- Maria Fátima Horta
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 31270-901, Brazil
| | - Luciana Oliveira Andrade
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 31270-901, Brazil
| | - Érica Santos Martins-Duarte
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 31270-901, Brazil
| | - Thiago Castro-Gomes
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, CEP 31270-901, Brazil
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9
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Abstract
Rhoptries are key secretory organelles for Toxoplasma gondii invasion. Here, we describe how to assess the ability of T. gondii tachyzoites to secrete their rhoptry contents in vitro.
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Affiliation(s)
| | - Melissa B Lodoen
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, USA
- Institute for Immunology, University of California, Irvine, Irvine, CA, USA
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier, Montpellier, France.
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Rastogi S, Cygan AM, Boothroyd JC. Translocation of effector proteins into host cells by Toxoplasma gondii. Curr Opin Microbiol 2019; 52:130-8. [PMID: 31446366 DOI: 10.1016/j.mib.2019.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/19/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022]
Abstract
The Apicomplexan parasite, Toxoplasma gondii, is an obligate intracellular organism that must co-opt its host cell to survive. To this end, Toxoplasma parasites introduce a suite of effector proteins from two secretory compartments called rhoptries and dense granules into the host cells. Once inside, these effectors extensively modify the host cell to facilitate parasite penetration, replication and persistence. In this review, we summarize the most recent advances in current understanding of effector translocation from Toxoplasma's rhoptry and dense granule organelles into the host cell, with comparisons to Plasmodium spp. for broader context.
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Abstract
One of the most successful intracellular parasites, Toxoplasma gondii has developed several strategies to avoid destruction by the host. These include approaches such as rapid and efficient cell invasion to avoid phagocytic engulfment, negative regulation of the canonical CD40-CD40L-mediated autophagy pathway, impairment of the noncanonical IFN-γ-dependent autophagy pathway, and modulation of host cell survival and death to obtain lifelong parasite survival. Different virulent strains have even evolved different ways to cope with and evade destruction by the host. This review aims to illustrate every aspect of the game between the host and Toxoplasma during the process of infection. A better understanding of all aspects of the battle between Toxoplasma and its hosts will be useful for the development of better strategies and drugs to control the parasite.
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Affiliation(s)
- Wanbo Zhu
- Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, Hefei, China.,Graduate School of Affiliated Anhui Provincial Hospital, Anhui Medical University, Hefei, China
| | - Jingyang Li
- Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, Hefei, China.,The Clinical Laboratory of the Third People's Hospital of Heifei, Hefei, China
| | - Faustina Pappoe
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Jilong Shen
- Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, Hefei, China
| | - Li Yu
- Department of Microbiology and Parasitology, Anhui Provincial Laboratory of Microbiology and Parasitology, Anhui Key Laboratory of Zoonoses, Anhui Medical University, Hefei, China
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Yang C, Broncel M, Dominicus C, Sampson E, Blakely WJ, Treeck M, Arrizabalaga G. A plasma membrane localized protein phosphatase in Toxoplasma gondii, PPM5C, regulates attachment to host cells. Sci Rep 2019; 9:5924. [PMID: 30976120 PMCID: PMC6459975 DOI: 10.1038/s41598-019-42441-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 03/25/2019] [Indexed: 11/17/2022] Open
Abstract
The propagation of Toxoplasma gondii is accomplished by repeated lytic cycles of parasite attachment to a host cell, invasion, replication within a parasitophorous vacuole, and egress from the cell. This lytic cycle is delicately regulated by calcium-dependent reversible phosphorylation of the molecular machinery that drives invasion and egress. While much progress has been made elucidating the protein kinases and substrates central to parasite propagation, little is known about the relevant protein phosphatases. In this study, we focused on the five protein phosphatases that are predicted to be membrane-associated either integrally or peripherally. We have determined that of these only PPM5C, a PP2C family member, localizes to the plasma membrane of Toxoplasma. Disruption of PPM5C results in a slow propagation phenotype in tissue culture. Interestingly, parasites lacking PPM5C divide and undergo egress at a normal rate, but have a deficiency in attaching to host cells. Both membrane localization and phosphatase activity are required for PPM5C’s role in attachment. Phosphoproteomic analysis show relatively few phosphorylation sites being affected by PPM5C deletion in extracellular parasites of which several are found on proteins involved in signaling cascades. This implies that PPM5C is part of a wider regulatory network important for attachment to host cells.
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Affiliation(s)
- Chunlin Yang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Malgorzata Broncel
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Caia Dominicus
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Emily Sampson
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - William J Blakely
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Moritz Treeck
- Signalling in Apicomplexan Parasites Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA. .,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA.
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Díaz-Martín RD, Mercier C, Gómez de León CT, González RM, Pozos SG, Ríos-Castro E, García RA, Fox BA, Bzik DJ, Flores RM. The dense granule protein 8 (GRA8) is a component of the sub-pellicular cytoskeleton in Toxoplasma gondii. Parasitol Res 2019; 118:1899-918. [PMID: 30949853 DOI: 10.1007/s00436-019-06298-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/18/2019] [Indexed: 12/24/2022]
Abstract
After host cell invasion, Toxoplasma secretes a variety of dense granule proteins (GRA proteins) from its secretory dense granules, which are involved in the biogenesis of the parasitophorous vacuole (PV). TgGRA8I is predicted to contain proline-rich domains, which are structural features of some cytoskeleton-related proteins. In agreement with this observation, previous proteomic analyses revealed the presence of TgGRA8I in the Toxoplasma sub-pellicular cytoskeleton. In the present study, we show (1) by docking analyses that TgGRA8I may interact with both Toxoplasma β-tubulin and actin; (2) by immunoelectron microscopy, proteomic, biochemical, and cellular approaches that TgGRA8I associates with sub-pellicular microtubules and actin at the parasite sub-pellicular cytoskeleton; (3) that type I parasites (RH strain) lacking the GRA8 gene (RHΔku80Δgra8) exhibit loss of conoid extrusion, diminished cell infection, and egress capabilities, and that these motility impairments were likely due to important alterations in their sub-pellicular cytoskeleton, in particular their sub-pellicular microtubules and meshwork. Parasites lacking the GRA4 gene (RHΔku80Δgra4) did not show modifications in the organization of the sub-pellicular cytoskeleton. Collectively, these results demonstrated that TgGRA8I is a dense granule protein that, besides its role in the formation of the PV, contributes to the organization of the parasite sub-pellicular cytoskeleton and motility. This is the first proline-rich protein described in the Toxoplasma cytoskeleton, which is a key organelle for both the parasite motility and the invasion process. Knowledge about the function of cytoskeleton components in Toxoplasma is fundamental to understand the motility process and the host cell invasion mechanism. Refining this knowledge should lead to the design of novel pharmacological strategies for the treatment against toxoplasmosis.
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Zhang D, Jiang N, Chen Q. ROP9, MIC3, and SAG2 are heparin-binding proteins in Toxoplasma gondii and involved in host cell attachment and invasion. Acta Trop 2019; 192:22-29. [PMID: 30664845 DOI: 10.1016/j.actatropica.2019.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/19/2018] [Accepted: 01/02/2019] [Indexed: 12/12/2022]
Abstract
Toxoplasma gondii (T. gondii) is an obligatory intracellular parasite that can infect varieties of warm-blooded animals, including humans and birds. Heparan sulfate (HS) is widely distributed on the eukaryotic cell surface of vertebrates and can inhibit T. gondii invasion. In this study, we investigated the transcription and expression of the level of TgROP9, TgMIC3, and TgSAG2 in T. gondii RH strain, and found that the expression levels of these three proteins in invading parasites were higher compared to those free ranging parasites. The recombinant proteins showed specific binding activity to both heparin and host cell surface. Incubation of these proteins with the host cells could block T. gondiiinvasion. Furthermore, protein-specific antibodies also blocked parasite invasion. Antibodies in the sera of T. gondii infected individuals recognized the recombinant TgROP9, TgMIC3, and TgSAG2, which suggested the exposure of these proteins to human immune system. Mice immunized with the three proteins exhibited protective immunity against lethal challenge. The data collectively suggested that these parasitic proteins may be used as candidate antigens for development of anti-toxoplasmosis vaccine.
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